Nim

How to play Nim

1. A row of matches is laid out. Players take turns.
2. On your turn, take 1, 2 or 3 matches.
3. Whoever takes the last match loses.
4. Play against the computer, or choose 2 players for a game with a friend.

Tips

• Count backward: leave your opponent exactly 1 match and you win.
• The magic numbers are 1, 5, 9, 13, 17, 21: try to leave your opponent one of them.
• If your opponent leaves you a magic number, take just 1 and wait for a mistake.
• On Hard the computer never errs: only the right strategy wins, and it does every time.
• On Easy and Medium, and with two players, Undo takes back your last move along with the computer's answer. On Hard, every move counts.

About Nim

Nim is a mathematical game with a long history and a hidden secret: there is a winning strategy, and once you find it, you can win every game you start from a good position.

This is the classic version where taking the last match loses. On Easy and Medium the computer makes mistakes; on Hard it plays perfectly, but you always start from a position you can win.

Points and badges

Finishing a game of Nim earns points for your level. Four badges are waiting in this game, from bronze to diamond: each one says what to do and adds bonus points.

Questions